The Food and Drug Administration approved buprenorphine for the treatment of opioid dependence and qualified physicians may treat opioid dependence in their practices. Reports suggest, however, that adoption of the medication has been slow. Studies of the use of buprenorphine in practice settings may help identify barriers to more widespread utilization. This study examines the use of buprenorphine within two large group health plans (Kaiser Permanente Northwest and Northern California). Data on services provided to members with diagnoses of opioid dependence will be extracted from administrative data systems for the period before (2000 - 2002) and after (2003 - 2008) FDA approval of buprenorphine. Utilization patterns are assessed and costs are estimated. Patient and practitioner interviews complement the quantitative analyses, add detail on trends, and suggest influences on the use of buprenorphine as a detoxification and maintenance medication. The investigation has three specific aims: Aim 1: Describe health care and addiction medicine services provided to members with a diagnosis of opioid dependence in two health plans (e.g., use of primary care, hospitalization, emergency care and addiction medicine including buprenorphine, clonidine, methadone, and counseling services). Aim 2: Examine the health plan and patient costs associated with services provided to patients with diagnoses of opioid dependence and assess the impact of buprenorphine on those costs (estimate annual costs, compare patients with and without buprenorphine, and assess patient costs). Aim 3: Identify factors that facilitate and inhibit the adoption and use of buprenorphine through interviews with 530 patients and 96 practitioners and administrators.